With Skyrim due out later this year, I suppose it's probably a good idea to do a little brushing up on our knowledge of The Elder Scrolls series and its lore... and this "Top 10 Gods of The Elder Scrolls" feature over at IGN seems like a good place to start.
There's apparently some confusion over whether or not Alduin is simply the Nordic interpretation of Akatosh (more on him later), but I'm going to assume otherwise for the purpose of this extremely important list. Let the nerds sort it out in the comments section. Yes, Akatosh takes the form of a dragon when he's upset, and Alduin hangs out in Nord country, which is full of dragons. But that's where the similarity stops. For starters, Akatosh doesn't usually destroy worlds and bring about the apocalypse. Alduin is also much scarier than Akatosh, who just sort of hangs around until he's needed. Alduin -- get this -- once ate the ages of everyone in Skyrim until they were all six years old. That's just weird and unexpected; the kind of thing a scary god should do. Bravo, Alduin.
Ah, Akatosh. If the power of a god derives in part from his sheer age, then Aka is the biggest and baddest of them all. How many gods can say they formed in "the Beginning Place"? Yeah, that's what I thought. The goofy necklace that Patrick Stewart wears at the beginning of Oblivion? That's the Amulet of Kings, and its destruction summoned Akatosh in the form of an enormous flaming dragon. It was Akatosh who defeated Mehrunes Dagon and saved Cyrodil from being sucked into Oblivion. Aka is one of only two deities to appear in every single religion in Tamriel; even most of the dirty elves acknowledge him!